The following processes are known for the production of aminohalo ketones.
(1) A process for producing a chloroketone or an aminochloroketone which comprises converting an amino-protected amino acid to a mixed acid anhydride, reacting the anhydride with diazomethane to give an amino diazoketone and treating the ketone with hydrochloric acid (Siegfried Fittkau et al., Journal fur Praktische Chemie, 529, 1986).
(2) A process for producing an aminochloroketone which comprises converting an amino-protected amino acid to a mixed acid anhydride, reacting the anhydride with diazomethane to give an aminodiazoketone, and treating the ketone with a metal chloride (Japanese Kokai Publication Hei-5-117169).
(3) A process for producing a chloroketone or an aminochloroketone which comprises reacting an amino-protected amino acid ester with a halomethyllithium (J. Chem. Soc. Chem. Commun., 969, 1994).
As the production technology for aminohalohydrins and aminoepoxides, the following processes are known.
(4) A process comprising reducing an .alpha.-chloroketone as typically obtained by the above process (1) or (2) to a .alpha.-halohydrin using a reducing agent such as sodium borohydride and a process comprising treating said .alpha.-halohydrin further with a base to give the corresponding epoxide (Tetrahedron, 50, 6333, 1994; J. Medic. Chem., 37, 1738, 1994; J. Medic. Chem., 34, 1221, 1991).
(5) A process comprising permitting sulfoniumylide to act on an amino-protected aminoaldehyde to give an epoxide (Tetrahedron Lett., 30, 3425, 1989; J. Org. Chem., 50, 4615, 1985).
(6) A process comprising permitting a peracid to act on an amino-protected allylamine derivative to synthesize an epoxide (Tetrahedron Lett., 35, 4939, 1994).
(7) A process comprising permitting a halomethyllithium to act on an amino-protected .alpha.-aminoaldehyde to produce an aminoepoxide (WO 93/23388).
Processes (1) and (2), wherein the explosive diazomethane is employed, are not satisfactory as industrial processes. Process (3) can hardly be implemented on an industrial scale partly because a low reaction temperature not exceeding -70.degree. C. is essential and partly because it is applicable only to special cases using dibenzyl group as an amino-protecting group.
Further, process (4) comprising reducing chloroketones to chlorohydrins is not flawless in industrial applicability because there is no established industrial production technology for chloroketones. Processes (5), (6) and (7) for the production of epoxides are disadvantageous in that epoxides of the threo configuration are preferentially produced, with the erythro-epoxides being not obtainable unless special amino-protecting groups are employed.